Influence of raw material properties upon critical quality attributes of continuously produced granules and tablets

Continuous manufacturing gains more and more interest within the pharmaceutical industry. The International Conference of Harmonisation (ICH) states in its Q8 'Pharmaceutical Development' guideline that the manufacturer of pharmaceuticals should have an enhanced knowledge of the product performance over a range of raw material attributes, manufacturing process options and process parameters. This fits further into the Process Analytical Technology (PAT) and Quality by Design (QbD) framework. The present study evaluates the effect of variation in critical raw material properties on the critical quality attributes of granules and tablets, produced by a continuous from-powder-to-tablet wet granulation line. The granulation process parameters were kept constant to examine the differences in the end product quality caused by the variability of the raw materials properties only. Theophylline-Lactose-PVP (30-67.5-2.5%) was used as model formulation. Seven different grades of theophylline were granulated. Afterward, the obtained granules were tableted. Both the characteristics of granules and tablets were determined. The results show that differences in raw material properties both affect their processability and several critical quality attributes of the resulting granules and tablets.

Simultaneous UV imaging and raman spectroscopy for the measurement of solvent-mediated phase transformations during dissolution testing

The current work reports the simultaneous use of UV imaging and Raman spectroscopy for detailed characterization of drug dissolution behavior including solid-state phase transformations during dissolution. The dissolution of drug substances from compacts of sodium naproxen in 0.1 HCl as well as theophylline anhydrate and monohydrate in water was studied utilizing a flow-through setup. The decreases in dissolution rates with time observed by UV imaging were associated with concomitant solid form changes detected by Raman spectroscopy. Sodium naproxen and theophylline anhydrate were observed to convert to the more stable forms (naproxen, and theophylline monohydrate) within approximately 5 min. Interestingly, the new approach revealed that three intermediate forms are involved in the dissolution process prior to the appearance of the neutral naproxen during dissolution in an acidic medium. The combination of UV imaging and Raman spectroscopy offers a detailed characterization of drug dissolution behavior in a time-effective and sample-sparing manner.

Miniaturized approach for excipient selection during the development of oral solid dosage form

The present study introduces a miniaturized high-throughput platform to understand the influence of excipients on the performance of oral solid dosage forms during early drug development. Wet massing of binary mixtures of the model drug (sodium naproxen) and representative excipients was followed by sieving, drying, and compaction of the agglomerated material. The mini-compacts were subjected to stability studies at 25°C/5% relative humidity (RH), 25°C/60% RH and 40°C/75% RH for 3 months. The physical stability of the drug was affected by the storage condition and by the characteristics of the excipients, whereas all the samples were chemically stable. Force-distance curves obtained during the compression of agglomerated material were used for the comparison of compressibility of different drug-excipient mixtures. The agglomerated drug-excipient mixtures were also subjected to studies of the dissolution trend under sequential pH conditions to simulate pH environment of gastrointestinal tract. Major factors affecting the dissolution behavior were the diffusion layer pH of the binary mixtures and the ability of the excipients to alter the diffusion layer thickness. The proposed approach can be used for excipient selection and for early-stage performance testing of active pharmaceutical ingredient intended for oral solid dosage form.

Structures of cefradine dihydrate and cefaclor dihydrate from DFT-D calculations

The crystal structure of cefradine dihydrate, C16H19N3O4S·2H2O, is considered in the pharmaceutical sciences to be the epitome of an isolated-site hydrate. The structure from single-crystal X-ray data was described in 1976, but atomic coordinates were not published. The atomic coordinates are determined here by combining the information available from the published single-crystal data with a dispersion-corrected density functional theory (DFT-D) method that has been validated to reproduce molecular crystal structures very accurately. Additional proof for the correctness of the structure comes from comparison with cefaclor dihydrate, C15H14ClN3O4S·2H2O, which is isomorphous and for which more complete single-crystal data are available. H-atom positions have not previously been published for either compound. The DFT-D calculations confirm that both cefradine and cefaclor are present in the zwitterionic form in the two dihydrate structures. A potential ambiguity concerning the orientation of the cyclohexadienyl ring in cefradine dihydrate is also clarified, and on the basis of the calculated energies it is shown that disorder should not be expected at room temperature. The DFT-D methods can be applied to recover full structural data in cases where only partial information is available, and where it may not be possible or desirable to obtain new experimental data.

Fuzzy Logic-based expert system for evaluating cake quality of freeze-dried formulations

Freeze-drying of peptide and protein-based pharmaceuticals is an increasingly important field of research. The diverse nature of these compounds, limited understanding of excipient functionality, and difficult-to-analyze quality attributes together with the increasing importance of the biosimilarity concept complicate the development phase of safe and cost-effective drug products. To streamline the development phase and to make high-throughput formulation screening possible, efficient solutions for analyzing critical quality attributes such as cake quality with minimal material consumption are needed. The aim of this study was to develop a fuzzy logic system based on image analysis (IA) for analyzing cake quality. Freeze-dried samples with different visual quality attributes were prepared in well plates. Imaging solutions together with image analytical routines were developed for extracting critical visual features such as the degree of cake collapse, glassiness, and color uniformity. On the basis of the IA outputs, a fuzzy logic system for analysis of these freeze-dried cakes was constructed. After this development phase, the system was tested with a new screening well plate. The developed fuzzy logic-based system was found to give comparable quality scores with visual evaluation, making high-throughput classification of cake quality possible.

Tailored beads made of dissolved cellulose--investigation of their drug release properties

In the frame of this work, we have investigated drug entrapping and release abilities of new type of porous cellulose beads (CBs) as a spherical matrix system for drug delivery. For that purpose, CBs prepared with three different methods were used as drug carriers and three compounds, anhydrous theophylline (Thp), riboflavin 5'-phosphate sodium (RSP) and lidocaine hydrochloride monohydrate (LiHCl) were used as model drug substances. The loading procedure was carried out by immersing swollen empty beads into the solutions of different concentrations of model drugs. The morphology of empty and loaded beads was examined using a field emission scanning electron microscopy (FE-SEM). Near-infrared (NIR) imaging was performed to identify the drug distributions on and within the loaded CBs. The drug amount incorporated into CBs was examined spectrophotometrically and in vitro drug release studies were performed to determine the drug release rates. The results of FE-SEM and chemical NIR imaging analyses revealed that incorporated drug were distributed on the surface and but also within the internal structure of the CBs. Physical properties of CBs and solubility of model drugs had effect on loading efficacy. Also, the drug release rates were controlled by solubility of model drugs (diffusion controlled release). In conclusion, CBs from dissolved cellulose show promise in achieving controlled drug delivery.

Engineering of an inhalable DDA/TDB liposomal adjuvant: a quality-by-design approach towards optimization of the spray drying process

PURPOSE

The purpose of this study was to identify and optimize spray drying parameters of importance for the design of an inhalable powder formulation of a cationic liposomal adjuvant composed of dimethyldioctadecylammonium (DDA) bromide and trehalose-6,6'-dibehenate (TDB).

METHODS

A quality by design (QbD) approach was applied to identify and link critical process parameters (CPPs) of the spray drying process to critical quality attributes (CQAs) using risk assessment and design of experiments (DoE), followed by identification of an optimal operating space (OOS). A central composite face-centered design was carried out followed by multiple linear regression analysis.

RESULTS

Four CQAs were identified; the mass median aerodynamic diameter (MMAD), the liposome stability (size) during processing, the moisture content and the yield. Five CPPs (drying airflow, feed flow rate, feedstock concentration, atomizing airflow and outlet temperature) were identified and tested in a systematic way. The MMAD and the yield were successfully modeled. For the liposome size stability, the ratio between the size after and before spray drying was modeled successfully. The model for the residual moisture content was poor, although, the moisture content was below 3% in the entire design space. Finally, the OOS was drafted from the constructed models for the spray drying of trehalose stabilized DDA/TDB liposomes.

CONCLUSIONS

The QbD approach for the spray drying process should include a careful consideration of the quality target product profile. This approach implementing risk assessment and DoE was successfully applied to optimize the spray drying of an inhalable DDA/TDB liposomal adjuvant designed for pulmonary vaccination.

Towards better process understanding: chemometrics and multivariate measurements in manufacturing of solid dosage forms

The manufacturing of tablets involves many unit operations that possess multivariate and complex characteristics. The interactions between the material characteristics and process related variation are presently not comprehensively analyzed due to univariate detection methods. As a consequence, current best practice to control a typical process is to not allow process-related factors to vary i.e. lock the production parameters. The problem related to the lack of sufficient process understanding is still there: the variation within process and material properties is an intrinsic feature and cannot be compensated for with constant process parameters. Instead, a more comprehensive approach based on the use of multivariate tools for investigating processes should be applied. In the pharmaceutical field these methods are referred to as Process Analytical Technology (PAT) tools that aim to achieve a thorough understanding and control over the production process. PAT includes the frames for measurement as well as data analyzes and controlling for in-depth understanding, leading to more consistent and safer drug products with less batch rejections. In the optimal situation, by applying these techniques, destructive end-product testing could be avoided. In this paper the most prominent multivariate data analysis measuring tools within tablet manufacturing and basic research on operations are reviewed.

Designing CAF-adjuvanted dry powder vaccines: spray drying preserves the adjuvant activity of CAF01

Dry powder vaccine formulations are highly attractive due to improved storage stability and the possibility for particle engineering, as compared to liquid formulations. However, a prerequisite for formulating vaccines into dry formulations is that their physicochemical and adjuvant properties remain unchanged upon rehydration. Thus, we have identified and optimized the parameters of importance for the design of a spray dried powder formulation of the cationic liposomal adjuvant formulation 01 (CAF01) composed of dimethyldioctadecylammonium (DDA) bromide and trehalose 6,6'-dibehenate (TDB) via spray drying. The optimal excipient to stabilize CAF01 during spray drying and for the design of nanocomposite microparticles was identified among mannitol, lactose and trehalose. Trehalose and lactose were promising stabilizers with respect to preserving liposome size, as compared to mannitol. Trehalose and lactose were in the glassy state upon co-spray drying with the liposomes, whereas mannitol appeared crystalline, suggesting that the ability of the stabilizer to form a glassy matrix around the liposomes is one of the prerequisites for stabilization. Systematic studies on the effect of process parameters suggested that a fast drying rate is essential to avoid phase separation and lipid accumulation at the surface of the microparticles during spray drying. Finally, immunization studies in mice with CAF01 in combination with the tuberculosis antigen Ag85B-ESAT6-Rv2660c (H56) demonstrated that spray drying of CAF01 with trehalose under optimal processing conditions resulted in the preservation of the adjuvant activity in vivo. These data demonstrate the importance of liposome stabilization via optimization of formulation and processing conditions in the engineering of dry powder liposome formulations.

A new approach to dissolution testing by UV imaging and finite element simulations

PURPOSE

Most dissolution testing systems rely on analyzing samples taken remotely from the dissolving sample surface at different time points with poor time resolution and therefore provide relatively unresolved temporally and spatially information on the dissolution process. In this study, a flexible numerical model was combined with a novel UV imaging system, allowing monitoring of the dissolution process with sub second time resolution.

METHODS

The dissolution process was monitored by both effluent collection and UV imaging of compacts of paracetamol. A finite element model (FEM) was used to characterize the UV imaging system.

RESULTS

A finite element model of the UV imaging system was successfully built. The dissolution of paracetamol was studied by UV imaging and by analysis of the effluent. The dissolution rates obtained from the collected effluent were in good agreement with the numerical model. The numerical model allowed an assessment of the ability of the UV imager to measure dissolution-time profiles. The simulation was able to extend the experimental results to conditions not easily obtained experimentally.

CONCLUSIONS

Combining FEM,experimental dissolution data and UV imaging provided experimental validation of the FEM model as well as a detailed description of the dissolution process.